When Will the Floods in Australia Stop?

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Flash flooding recently overwhelmed the Australian city of
Toowoomba, where rushing waters killed 16 people in a town that
is home to about 130,000 on Jan. 11.

The disaster in Toowoomba, about 60 miles (95 kilometers) west of
the state capital, Brisbane, was the latest in the
ongoing flooding that has killed more than 20 people and
affected more than 200,000 in the state of
Queensland since December. As the heavy rains continue to
fall and the death toll in Queensland rises, many want to know
when the flooding in Australia will end.

"This monsoonal system is in decline and will decay in a
relatively short period," said Greg Holland, a senior scientist
and severe weather expert at the University Corporation of
Atmospheric Research (UCAR) in Boulder, Colo. "There may be
follow-up systems, but we shall have to wait and see."

Kevin Trenberth, a climatologist with the National Center for
Atmospheric Research (NCAR) in Boulder, Colo., told
OurAmazingPlanet that "the worst is probably over." Yet even
after the rains stop, other factors will cause the water to stick
around, Holland said.

Make it rain

The flooding in Toowoomba and in many Australian cities has been
described as an " inland
tsunami," according to many news reports. These intense
floods were caused by a massive monsoon due to this year's
unusually strong La Niña — which is perhaps the strongest
ever recorded.

"All of this is fueled by the very high sea-surface temperatures
in the region," Trenberth said.

La Niña is the opposite phase of El Niño, or a cooling in the
central and eastern tropical Pacific Ocean. La Niñas create
stronger than normal trade winds that push warm water from the
tropics into the western Pacific. The waters around Australia are
now the warmest ever measured. As this warm ocean water
evaporates, moisture fills the atmosphere and fuels intense
storms.

The record ocean temperatures have some scientists drawing a link
between climate change and the flooding in Australia.

"I think people will end up concluding that at least some of the
intensity of the monsoon in Queensland can be attributed to
climate change," Matthew England, of the Climate Change Research
Center at the University of New South Wales in Sydney,
told Reuters.

The oft-repeated line is that no one storm or event can be linked
directly to climate change, but Holland said, "There is also
undoubtedly a contribution from global warming."

Wet cycle

Even after the rains stop, the floodwaters will not disappear
overnight. Water in southeast Queensland will drain to the sea,
but the water in north-central Queensland will likely head
southwest, and could take up to six months to move down through
the center of the continent, Holland said.

The water that hangs around will become a massive, hot, inland
sea that will create moist air and drive intense local rains
similar to what happened in Toowoomba.

Lake Eyre, which sits below sea level in the south-center of the
country, may become filled with draining floodwater. This is good
news for the plants and animals around the lake, Holland said,
but the water will also provide more moisture for future rains in
southeast Australia.

"So you can see there is a long cycle that has commenced and will
last for many months yet," Holland said.